There are many requirements for the measurement of ionizing radiation. For example, nuclear power plants require measurements of radiation fields, radioactive isotope concentrations, etc.
Conventional analog radiation monitoring systems consist of a plurality of signal channels each consisting of a discrete remote radiation monitor and an analog circuit for converting the pulse output of the radiation monitor into an analog signal indicative of the radiation level. The output signal developed by the analog circuit is a voltage which is proportional to the log of the average frequency of the pulses developed by the remote radiation monitor. Typically this voltage output is utilized to drive a visual display or actuate an alarm. The analog format of the radiation information of conventional analog radiation systems is not suitable for rapid complex analysis.
Further, the nuclear decays typically encountered result in a random frequency of pulses from the radiation detectors and the inherent nature of the analog circuit is such that it is extremely difficult to design a radiation monitoring system which exhibits both a low statistical error and a response time sufficiently fast to detect changes. This is due to the fact that a low statistical error requires averaging over a very long period of time which in turn implies a very slow response time for the analog radiation monitoring system.
Prior art analog systems inherently average for a fixed time. Thus, the design includes a fixed trade-off between statistical error and response time.